The production of organic compounds from synthesis gas has been carried out for a significant period of time. It is well known that one can produce methanol from synthesis gas and that methanol can be further reacted by hydroformylation, homologation and carbonylation reactions to produce acetaldehyde, ethanol and acetic acid, respectively. The difficulties, however, have resided in the ability to carry out one of these chosen reactions to selectively produce the desired compound at an acceptable conversion rate.
In the case of methanol hydroformylation the reaction is generally preferably catalyzed using a mixture of a cobalt compound and a halogen as the promoter, though many other metal compounds and promoters have been tried. In addition, the prior art has disclosed the use of secondary activators in conjunction with the metal catalysts and promoters. These secondary activators can be other metallic salts or compounds, amines, phosphorus compounds and a multitude of other compounds that have been disclosed in the published literature. Thus, a typical catalyst system contains the metal catalyst, the promoter and the secondary activator. Though a significant amount of literature does exist, to our knowledge it does not disclose or suggest our improved invention.
In U.S. Pat. No. 3,356,734, issued to Kuraiski et al. on Dec. 5, 1967, there is disclosed the process for producing acetaldehyde using a cobalt catalyst promoted by a halogen promoter. It makes no reference to trivalent nitrogen or trivalent phosphorus compounds.
U.S. Pat. No. 4,151,208, issued to Pretzer et al. on Apr. 24, 1979, claims the use of cobalt (II) tetraaromaticporphine compounds as catalysts and an iodine promoter to improve selectivity. The only selectivity value reported was about 62 mole percent.
The use of a halide-free catalyst is disclosed in U.S. Pat. No. 4,201,868, issued to Slinkard on May 6, 1980. The halide-free catalysts is a cobalt carbonyl in complex combination with an organic nitrogen compound.
On Sept. 30, 1980, U.S. Pat. No. 4,225,517 was issued to Gane. This patent claims a process for the production of acetaldehyde in the presence of a cobalt catalyst, an iodine or bromine promoter, one of the elements arsenic, antimony or bismuth and the additional presence of an additive which can be an inert liquid, or an acid or acid derivative, or an oxygen-containing compound, or a non-polar solvent. These selectivities reported are below 60%. In column 10, lines 5 and 6, Gane indicates that the use of a trivalent phosphorus compound resulted in the production of ethanol as the major product rather than the production of acetaldehyde.
In Japanese Publications Nos. 77/136110, and 77/136111, filed by Saito et al. and published on Nov. 14, 1977, there are disclosed cobalt catalysts promoted with an iodine compound and employing a phosphorus compound. In neither publication is there any mention of the trivalent nitrogen compounds and both show low selectivities.
Japanese Publication No. 77/133914, filed by Saito et al. and published on Nov. 9, 1977, relates to the use of cobalt, a halide promoter and at least one element of the group, arsenic, antimony and bismuth. There was no disclosure of trivalent nitrogen or trivalent phosphorus compounds and selectivities were low.
In an article by Pretzer and kobylinski, Annals New York Academy of Sciences, 333,58 (1980), the authors discussed the methanol carbonylation reaction. On page 60 they noted total inhibition of the cobalt catalyst was observed when n-butylamine was used in the catalyst charge in addition to cobalt acetoacetate and iodine. They also noted that addition of triphenylphosphine enhanced the selectivity to ethanol at the expense of all other potential products.